Lancing devices are used for obtaining capillary blood from body sites. A typical user of a lancing device is a person in a program of self-blood glucose monitoring for treatment of diabetes. Such a user presses a lancing device at a selected puncture site, activates the lancing device to puncture the skin at the site, and draws capillary blood for testing. To minimize any discomfort caused by the puncture, the lancing device typically controls the depth of the puncture, quickly withdraws the lancet from the skin once a puncture has been made, and prevents the lancet from rebounding and reentering the puncture or causing a second puncture.
Once a puncture has been made, the lancing device remains on the site and a vacuum is created to draw skin partially into an end cap of the device. As this occurs, a small amount of blood forms on the skin at the puncture. The vacuum is then released and the lancing device is removed from the skin. The drop of blood on the surface of the skin at the puncture site is then applied to a test sensor.
These lancing devices include a gasket connected to the lancet that reciprocates in the lancing device as the lancet moves through a lancing stroke. The gasket is in airtight contact with the inside of the lancing device such that as the gasket slides within the lancing device, air is displaced and a vacuum is created. The necessity for the airtight contact between the gasket and the inside of the lancing device requires precision molding of the parts which increases the cost of the device.
In addition, friction between the gasket and lancet device reduces the speed of the lancet which can increase the pain experienced by a user. This friction also increases the force required to actuate the lancet making the lancet device harder to operate. Also, the airtight fit can quickly start to leak if dirt gets between the gasket and the lancet device. A gasket also limits the configuration of the devices to a round shape and may limit the possible uses of the lancet devices as part of a test sensor.